The present invention relates to new lubricating oil additives which impart to lubricating oils good detergent, dispersing and anti-rust properties. This invention relates also to lubricating oils and to fuels and carburants containing said additives.
There are known to the prior art, additives for lubricating oils which consist of derivatives of carboxylic acids substituted with slightly unsaturated hydrocarbons. This class of additives, which has been known for some years, was an important development to the lubricating oil art. They consist mainly of reaction products of carboxylic acid acylating agents, substituted with a fairly saturated hydrocarbon radical containing an aliphatic chain of at least 30 carbon atoms, preferably 50 carbon atoms, with amines or alcohols.
Lubricating oil additives in the nature of acylated amines produced from the reaction of substituted carboxylic acid acylation agents with amines, such as disclosed in U.S. Pat. No. 3,172,892, granted Mar. 9, 1965, are known for their desirable dispersing properties, especially with regard to sludge. A "sludge" is the product formed in a motor crank case when the temperature of the lubricating agent in the crank case is alternately low and high or maintained at a low temperature in a continuous way. This last condition frequently occurs in urban traffic in what is frequently referred to as "door to door" travel at low speeds. Low operating temperatures favor water formation and accumulation within the lubricating agent. The combination of condensed water, of curburant and lubricating agent, decomposition products, and of oil forms the sludge. This sludge, which is not readily dispersed, may be damaging to the operation of a motor.
Lubricating agent additives in the form of esters resulting from the reaction of the same foregoing acylation agents with alcohols or phenols are efficient anti-rust agents and reasonably good detergents. Products of this nature are disclosed in U.S. Pat. No. 3,381,022, granted Apr. 30, 1968. The dispersing action of these additives is, however, limited by their relatively low thermal stability, by their lack of resistance to hydrolysis, and by their acidity.
It is an object of the present invention to provide a lubricating oil additive which does not have the shortcomings of the prior art additives.
It is also an object of the present invention to provide lubricating oils containing the new additives and which oils have improved dispersing, detergent and anti-rust properties.
Another object of the present invention is the provision of a lubricating oil additive having improved properties over those of the prior art alkyl substituted carboxylic acid esters described, for example, in U.S. Pat. No. 3,381,022, and also with regard to the amide derivatives described in the U.S. Pat. No. 3,172,892.
Other objects of the invention will be apparent to those skilled in the art from the present description.